Answer:
Birth defects are abnormalities that occur in babies during pregnancy or childbirth. They can be caused by a variety of factors, including genetic mutations, exposure to harmful substances, and certain infections. Here are the four main causes of birth defects, along with examples of each:
Genetic causes: Genetic mutations or alterations in chromosomes can lead to birth defects. For example, Down syndrome is caused by an extra copy of chromosome 21. This extra genetic material leads to developmental delays, intellectual disability, and characteristic physical features.
Environmental causes: Exposure to certain substances during pregnancy can cause birth defects. For example, if a pregnant woman drinks alcohol, the developing baby may be born with fetal alcohol syndrome, which can cause intellectual disability, behavioral problems, and physical abnormalities.
Nutritional causes: Poor nutrition during pregnancy can also lead to birth defects. For example, a lack of folic acid, a type of B vitamin, can lead to neural tube defects, such as spina bifida, in which the spinal cord doesn't develop properly.
Infectious causes: Certain infections that a woman can get during pregnancy can cause birth defects in the developing fetus. For example, if a pregnant woman contracts rubella (also known as German measles), the developing baby may be born with congenital rubella syndrome, which can cause hearing and vision problems, intellectual disability, and heart defects.
It's worth noting that many birth defects are caused by a combination of factors, and sometimes the exact cause is not known. Additionally, some birth defects may not be preventable, but steps can be taken to reduce the risk of certain types of birth defects. Prenatal care, including regular check-ups and screenings, is important to help identify any potential problems early on in pregnancy.